Question

Solve the following quadratic equation using quadratic formula: $x^2-7x+12=0$

• A. $\{4,3\}$
• B. $\{4,-3\}$
• C. $\{-4,-3\}$
• D. None of these

Answer 1

Answer: (A)

$\{4,3\}$

$\Rightarrow$ The given quadratic equation is $x^2-7x+12=0$, comparing it with $a{x}^2+bx+c=0$

$\Rightarrow$ We get, $a=1,b=-7,c=12$

$\Rightarrow$ $x=\frac{-b\pm \sqrt{b^2-4ac}}{2a}$

$=\frac{-(-7)\pm \sqrt{(-7{)}^2-4(1\left)\right(12)}}{2\left(1\right)}$

$=\frac{7\pm \sqrt{49-48}}{2}$

$=\frac{7\pm \sqrt{1}}{2}$

$=\frac{7\pm 1}{2}$

$\Rightarrow$ $x=\frac{7+1}{2}$ and $x=\frac{7-1}{2}$

$\therefore$ $x=4$ and $x=3$